It’s in the instructions. BIP32 standard/BIP39 standardYour missing the point, that recovery phase/seed is not your Crypto Private keys, it tells the hardware wallet what keys to use for that seed for the different coins private address's. No one knows the actual private address and is not retrievable, you have to rely on replacing the original wallet if lost, stolen or damaged. Show how to retrieve the Secret (Private) key from the hardware wallet for BTC where I can use that Private Key in another wallet like a web wallet, QT wallet etc. not depending upon their business, network and software.
Why do you think they warn you that if you lose control of your 24 word seed your wallet is completely compromised and can be taken over at will? Web search of Reddit comes up with these questions answered repeatedly that you are not locked behind the hardware wallet if you know the 24 world mnemonic phrase.
And from a Trezor blog